My Audi A6 tdi 1.9 (2003) has an intermittent rough idling problem which just sounds like a miss fire. I have tried changing the mass airflow filter-not worked - now I have found that it could be a faulty injector loom , does anyone know if my engine has to be dropped or not when installing it ?

Good afternoon Michael

The good news is that you have power and your starter is working. If you can't get it started, and had rough idle before that, there are a couple of high likelihood directions to go, so lets start with the least painful.

For proper ignition, you need three things - air, spark, and fuel. If you get the wrong mix, rough running or none. Since you went from running rough to not turning over, you are likely being choked off from one of the vital three (An engaging starter is also needed, but it sounds like you have that)

Not enough air would most likely be a dirty or clogged air filter. There are lots of Youtube videos on how to access and change the filter, such as ( How to change engine air filter on Audi A6 C6 4F 2 0 tdi ). I don't know if it's exactly the same on model, but it's likely pretty close. An auto parts store will be able to guide you to the specific replacement filter if it turns out to be in need of replacement. If you're stranded and not near an auto parts store, you can at least examine the filter and gently bang it out against a solid surface to dislodge overt dust bunnies (try not to breathe any of this, do it outside if you take this route). Also take a look at what's up with the filter. If it's just dust, it may have been overdue for replacement. Oil or other viscous liquid could be signs of more serious problems like an oil leak.

Lack of fuel would come from an old, clogged fuel filter, or clogged fuel injectors. Similarly, videos like this (
Fuel Filter Replacement Audi A6 ) can guide you on the filter, and (
How to Change an A6 Injector eHow ) or the like can guide you on fuel injectors. Try the filter first, less pain. Then if you can get it started, get a bottle of fuel injector cleaner, add it to fuel tank while topping off your fuel with fresh new fuel (in case you got some bad gas), and see if performance picks up over then next 50 miles or so.

Finally, lack of spark. When is the last time the spark plugs were replaced? Worn, corroded or fouled plugs will give you dismal performance. See (
How to change your Audi A4 A6 or A8 Spark plugs and Coils ) and similar for how to on that. eBay is a good place to shop for the plugs, at least for lower mark-up. The procedures will also let you examine the electrical connections for wear. There are also usually seals around the coil packs to keep water splash out of the engine. Make sure the seals aren't all turned to crumbly black gunk (this'd be a sign to replace the coils, or at leas the gaskets.

There are plenty of other things that could be the issue, but with the slow decline into rough running, the odds are pretty good that something in the above will get you running.

Good Luck. If this is helpful, clicking it as helpful will be appreciated.

Cheers!

Is your check engine light coming on? If so what are teh codes?

thanks
andy

sounds like you have a very dirty mass air flow meter. invest in a new one and be sure to clean the throttle body with an appropriate cleaner and tooth brush.

Sounds like,bad spark plug wires,time for an good tune up,wires,plugs,air filter.

You could have a bad air flow sensor. Do you also have a lack of power??

Sounds like the alternator is badly damaged. The alternator will drain the battery if the regulutor or diode assembly goes out and/or the alternator is seized or locking up, which will cause the smoke (belt slippage) and drag on the engine (rough idle).

i'm very convinced it is your mas airflow sensor!!! Had the same problem on my A4

Here ya go!

hello before you replace parts you might not need try to test the map sensor see if it is within range this works with vacuum changes in motor goodluck please rate